546 2×300 3.44000 =3.7, 1th of which is .7, therefore the power required to overcome the resistance occasioned by the weight and friction of the water will be 3.7+.7=4.4 H. P., 4.5 horse power. say EXAMPLE II. There is a cistern 20 feet square, and 10 feet deep, placed on the top of a tower 60 feet high, what power is requisite to fill the cistern in 30 minutes, and what will be the diameter of the pump, when the length of stroke is 2 feet, and making 40 per minute? 20 × 20 × 10-4000 cubic contents of cistern. √311.7 17.6 inches diameter of pump required. Founders generally prove the pipes they cast to stand a certain pressure, which is calculated by the weight of a perpendicular column of water, the area being equal to the area of the pipe, and the height equal to any given height. To ascertain the exact pressure of water to which a pipe is subjected, a safety valve is used, generally of 1 inch diameter, and loaded with a weight equal to the pressure required: for example, a pipe requires to stand a pressure of 300 feet, what weight will be required to load the safety valve one inch diameter? Feet. Inches Ounces. 300×12-3600X.7854-2827.4400×1000 16361 weight required. =102 lbs. 4 oz. Each of the weights for the safety valves of these hydrostatic proving machines are generally made equal to a pressure of a column of water 50 feet high, the area being the area of the valve. 50 feet of pressure on a valve 1 inch diam.-17.06 lbs. In pumping, there is always a deficiency owing to the escape of water through the valves; to account for this loss, there is an allowance of 3 inches for each stroke of piston rod: for example, a three feet stroke may be calculated at 2 feet 9 inches. There is a town, the inhabitants of which amount to 12000, and it is proposed to supply it with water from a river running through the low grounds 250 perpendicular feet below the best situation form the reservoir. It is required to know the power of an engine capable of lifting a sufficient quantity of water, the daily supply being calculated at 10 ale gallons to each individual: also what size of pump and pipes are requisite for such? 12000×10-120000 gallons per day. Engine is to work 12 hours, 120000 =10000 gallons per hour. The pump to have an effective stroke of 3 feet, and making 30 strokes per minute. 166.6 30 =5.5533 gallons each stroke. 282×5.6=1579.2 cubic inches of water each stroke. 1579.2 3 feet 9 inches-- =35.1 inches, area of pump. 35.1 .7854 =44.7, therefore √44.7-6.7 diameter of pump. The pipes will require to be at least the diameter of t pump; if they are a little more, the water will not require to flow so quickly through them, and thereby cause less friction. The power of the engine will be 166.6 gall. 10 lb. ×250 feet=426935 momentum. 426925 44000 426925 =9.7, add 1-5th-11.64 horse power 32000 |